Britain could rejoin the European Union within five years of applying, according to a new assessment promoted by pro-EU campaign organisation Best for Britain.
The study, How the UK joins the EU, and how long it would take, argues that membership could be achieved within a single parliamentary term if there is sustained political support on both sides.
Report points to existing alignment
The authors say Britain's previous membership and limited regulatory divergence since Brexit could help accelerate accession. They cite Finland's admission in less than three years as evidence that the process need not necessarily take a decade.
The estimate runs from submitting a membership application. It is not a prediction that Britain will automatically be back in the EU five years from today.
Political agreement would remain essential
In comments published by Best for Britain, former European Commission director-general Sir Jonathan Faull emphasised that accession would still involve complex negotiations, careful preparation and unanimous agreement among member states.
Faull said the timetable would depend on consistent political will in Britain and the EU. Sandro Gozi MEP also argued that a former member with substantial existing alignment could proceed faster than countries starting from a different regulatory position.
What the official accession process requires
The European Commission's guidance says negotiations cannot begin until all EU governments agree to a negotiating framework.
Applicants must demonstrate that they can adopt and enforce EU rules. Negotiations cover individual policy chapters, and their duration varies according to the country's progress.
An accession treaty must obtain the support of the relevant EU institutions, be signed by the applicant and existing member states, and be ratified by every participating country under its constitutional rules.
Finland's experience therefore offers a comparison, rather than a guaranteed timetable for Britain.
Campaign assessment, not an agreed timetable
The report does not announce a British government decision to apply, an EU commitment to admit the UK, or negotiated membership terms.
Its five-year claim should be understood as the campaign group's assessment of what could be possible, subject to political agreement and completion of the accession process.